Dental tri-ruler



FIG. 1 is a front elevational view of a dental tri-ruler showing the design;

FIG. 2 is a top elevational view thereof;

FIG. 3 is a bottom elevational view thereof;

FIG. 4 is a rear elevational view thereof; and,

FIG. 5 is a side elevational view thereof, the opposite side elevational view being a mirror image thereof. 

CLAIM The ornamental design for a dental tri-ruler, as shown and described. 